Multi-principal-element alloy added with interstitial atoms and preparation method of multi-principal-element alloy

Abstract

The invention relates to the technical field of alloy materials, and particularly discloses a multi-principal-element alloy added with interstitial atoms and a preparation method of the multi-principal-element alloy. The invention relates to a multi-principal element alloy added with interstitial atoms, which is characterized by consisting of 99.7 to 99.9 weight percent of CoNiCrMo alloy matrix and 0.1 to 0.3 weight percent of nitrogen element, the CoNiCrMo alloy matrix comprises the following components in percentage by element atoms: 33-37 at% of Co, 10-30 at% of Ni, 10-30 at% of Mo, and the balance of CoNiCrMo. Ni is equal to 33 to 37 at%; cr is equal to 18 to 22 at%; and Mo = 7-11 at%. The strength of the alloy is improved in an interstitial atom solution strengthening and cold rolling deformation mode, the FCC phase structure is stabilized through interstitial N atoms, the good plasticity of the alloy is kept while the strength of the alloy is improved, then the strength of the alloy is improved through cold rolling deformation, the strength and plasticity of the alloy are balanced, and the strength and plasticity of the alloy are improved. And the practical application of the alloy in a low-temperature environment is facilitated.

Description

Technical Field

[0001] The present application relates to the technical field of alloy materials, and in particular to a multi-principal-element alloy with added interstitial atoms and a preparation method thereof. Background Art

[0002] Most traditional alloy materials are dilute solid solutions, generally divided into solutes and solvents, while high entropy alloys are high-concentration solid solutions in which the solute and solvent cannot be separated. Due to the special composition of high entropy alloys, a high mixed entropy effect is produced, which stabilizes the formation of the solid solution phase, reduces the existence of the intermetallic compound phase, and tends to form a simple solid solution structure of a single-phase or multi-phase face-centered cubic structure (FCC), body-centered cubic structure (BCC) or hexagonal close-packed structure (HCP). The concept of multi-principal alloys is developed on the basis of the concept of high entropy alloys.

[0003] CoNiCrMo medium entropy alloy has excellent mechanical properties, high solid solution strengthening effect and good ductility, and its toughness is better than most traditional alloys and high entropy alloys. FCC phase is generally considered to have excellent plasticity and toughness, but its strength and hardness are not satisfactory.

[0004] Therefore, it is necessary to provide a new method to prepare multi-principal component alloys with excellent performance, achieve the matching of strength and plasticity of the alloys, and meet the application requirements of the alloys in extreme low temperature environments such as fusion superconductivity and extraterrestrial exploration. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a multi-principal element alloy with added interstitial atoms and a preparation method thereof.

[0006] In a first aspect, the present application provides a multi-principal alloy with added interstitial atoms, which is composed of 99.7-99.9wt% of a CoNiCrMo alloy matrix and 0.1-0.3wt% of nitrogen; Calculated by the atomic percentage of the elements, the composition of the CoNiCrMo alloy matrix is: Co=33-37at%; Ni=33-37at%; Cr=18-22at%; Mo=7-11at%.

[0007] Preferably, the multi-principal alloy with added interstitial atoms consists of 99.75-99.85wt% CoNiCrMo alloy matrix and 0.15-0.25wt% nitrogen; the composition of the CoNiCrMo alloy matrix is: Co=34-36at%; Ni=34-36at%; Cr=19-21at%; Mo=8-10at%.

[0008] Preferably, the multi-principal alloy with added interstitial atoms is composed of 99.75-99.85wt% CoNiCrMo alloy matrix and 0.15-0.25wt% nitrogen; the composition of the CoNiCrMo alloy matrix is: Co=34-36at%; Ni=34-36at%; Cr=19-21at%; Mo=8-10at%; P<0.001at%; S<0.0015at%. In a second aspect, the present application provides a method for preparing the multi-principal alloy with added interstitial atoms, which specifically comprises the following steps in sequence: S1: The materials are prepared according to the target composition ratio, and then placed in a vacuum pressure induction furnace, pressurized to 10-20 bar in an inert gas atmosphere for smelting to obtain an alloy mother ingot, which is then cast in a copper mold to obtain an alloy ingot; S2: Forging the alloy ingot to obtain alloy flat steel; S3: performing a solid solution treatment on the alloy flat steel treated in step S2 to obtain a solid solution multi-principal alloy; Alternatively, the alloy flat steel treated in step S2 is sequentially subjected to solid solution treatment, hot rolling treatment, heat treatment, cold rolling treatment, and annealing treatment to obtain a cold-rolled annealed multi-principal alloy.

[0009] The present application adds a multi-principal alloy of interstitial atoms, introduces a certain amount of nitrogen into the CoNiCrMo alloy, and forms an interstitial solid solution with the matrix. Through the processing technology of solid solution or solid solution + cold rolling, the alloy is recrystallized, twins can be induced under low temperature conditions, and the interstitial atoms stabilize the phase structure. The multiple dislocation mechanisms induce plastic enhancement, and the multiple strengthening effects further improve the strength and plasticity of the alloy. During the experiment, the applicant found that when the added nitrogen content is high, the plasticity and toughness of the alloy will be significantly reduced.

[0010] like Figure 1 The thermodynamic phase diagram of a multi-principal alloy with added interstitial atoms is shown in Figure 2. Figure 1 Analysis shows that when the solid solution temperature is 1100-1200℃, nitrogen exists in the alloy in a solid solution state and Cr will not precipitate. 2 N can ensure the stability of a single FCC phase, and the alloy strengthening mechanism is solid solution strengthening.

[0011] Preferably, in step S2, the blank forging temperature is 950-1150°C.

[0012] Furthermore, in step S2, the blank forging temperature is 1000-1100°C.

[0013] Preferably, in step S3, the solution treatment is specifically: keeping warm at 1100-1200° C. for 50-70 min.

[0014] Furthermore, in step S3, the solution treatment is specifically: keeping warm at 1120-1180° C. for 50-70 minutes.

[0015] Preferably, in step S3, the hot rolling treatment is specifically as follows: hot rolling reduction rate is 45-55%, multiple rolling passes are performed, and water cooling is performed to room temperature to obtain a hot rolled and cooled alloy plate.

[0016] Furthermore, in step S3, the hot rolling treatment is specifically as follows: the hot rolling reduction rate is 48-52%, multiple rolling passes are performed, and water cooling is performed to room temperature to obtain a hot-rolled and cooled alloy plate.

[0017] Preferably, in step S3, the heat treatment is specifically: keeping warm at 1100-1200° C. for 0.5-2 h, then cooling to room temperature and pickling.

[0018] Furthermore, in step S3, the heat treatment is specifically: keeping warm at 1120-1180° C. for 1-1.5 hours, then cooling to room temperature and pickling.

[0019] Preferably, in step S3, the cold rolling treatment is specifically: the cold rolling reduction rate is 10-90%, and multiple rolling passes are performed.

[0020] Furthermore, in step S3, the cold rolling process is specifically: the cold rolling reduction rate is 30-60%, and multiple rolling passes are performed.

[0021] Preferably, in step S3, the annealing treatment is specifically: annealing at 800-900° C. for 2-20 min.

[0022] Furthermore, in step S3, the annealing treatment is specifically as follows: annealing the alloy plate at 800°C for 2-8 min, 850°C for 2-8 min, and 900°C for 2-8 min.

[0023] The present application adopts interstitial atom solid solution strengthening and cold rolling deformation to improve the strength of the alloy, stabilizes the FCC phase structure by interstitial N atoms, improves the strength of the alloy while maintaining good plasticity of the alloy, and further improves the strength of the alloy by cold rolling deformation, so that the alloy is balanced in strength and plasticity, which is conducive to the practical application of the alloy in low temperature environment.

[0024] In summary, the technical solution of this application has the following effects: The present application adds a multi-principal alloy of interstitial atoms, introduces a certain amount of nitrogen into the CoNiCrMo alloy, and forms an interstitial solid solution with the matrix. Through the processing technology of solid solution or solid solution + cold rolling, the alloy is recrystallized, twins can be induced under low temperature conditions, and the interstitial atomic stable phase structure and multiple dislocation mechanisms induce plastic enhancement. The multiple strengthening effects further improve the strength and plasticity of the alloy. This alloy preparation method is simple and helps promote the application of multi-principal alloys in low temperature environments.

[0025] The multi-principal element alloy design with added interstitial atoms and the preparation method thereof solve the problems of insufficient low-temperature strength faced by the CoNiCrMo alloy, and coordinate the relationship between strength and plasticity through multiple verifications and adjustments.

[0026] The present invention also provides a reasonable combination of appropriate doping amounts and treatment processes, and can provide relatively rich performance control combination means, especially by maintaining the alloy at a higher temperature for a longer time, the forged structure is partially or completely eliminated, and part of the precipitated phase is dissolved to form a nearly single-phase structure. The alloy can then regain a larger performance controllable space on the basis of a higher performance level, and further strengthen it through a combination of deformation strengthening and precipitation strengthening to obtain a more reasonable combination of strength and plasticity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Thermodynamic phase diagram of multi-principal alloy with added interstitial atoms provided in this application.

[0028] Figure 2 Electron backscattered diffraction (EBSD) morphology of the microstructure of the solid solution multi-principal alloy with added interstitial atoms in Example 1 of the present application.

[0029] Figure 3 This is the tensile stress-strain curve of the solid solution multi-principal element alloy with added interstitial atoms prepared in Example 1 of the present application.

[0030] Figure 4 This is the tensile stress-strain curve of the cold-rolled annealed multi-principal alloy with added interstitial atoms prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0031] The present application is further described in detail below in conjunction with examples, comparative examples and performance testing experiments. These examples should not be construed as limiting the scope of protection claimed in the present application. Example

[0032] Example 1 Example 1 provides a multi-principal-element alloy with added interstitial atoms and a method for preparing the same.

[0033] The multi-principal alloy in this embodiment is composed of 99.8wt% CoNiCrMo alloy matrix and 0.2wt% nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=35at%; Ni=35at%; Cr=20at%; Mo=9at% The preparation method of the multi-principal alloy in this embodiment includes the following steps: S1: Batching and smelting According to the target composition ratio, 50 kg of single element raw materials of Co, Ni, Cr and Mo are calculated and weighed for use.

[0034] The uniformly mixed alloy elements and N element are placed in a vacuum induction furnace and smelted under a pressure of 1500 kPa in an inert gas atmosphere to obtain an alloy mother ingot, which is then cast in a copper mold to obtain an alloy ingot.

[0035] S2: Open forging The alloy ingot was forged at a final forging temperature of 1050°C into a 15mm thick flat steel. Samples were taken to test the uniformity of the composition, and the chemical composition met the alloy design standards.

[0036] S3: Solution treatment The forged alloy flat steel was kept in a heat treatment furnace at 1180° C. for 60 minutes and then water-cooled to room temperature to obtain a solid solution multi-principal alloy.

[0037] S4: Mechanical properties test of the obtained multi-principal alloy The alloy plates were cut into tensile specimens using an electric spark wire cutting machine, and the tensile mechanical properties of the alloy were tested using a universal mechanical testing machine. The test temperatures included 298K, 77K and 4.2K.

[0038] Performance at 4.2K temperature: tensile strength is 1720MPa, yield strength is 968MPa, and plasticity is 68%.

[0039] Performance at 77K temperature: tensile strength 1500MPa, yield strength 794MPa, plasticity 65.5%.

[0040] Performance at 298K temperature: tensile strength 947MPa, yield strength 437MPa, plasticity 57.5%.

[0041] Example 2 Example 2 provides a multi-principal element alloy with added interstitial atoms and a preparation method thereof.

[0042] The multi-principal alloy in this embodiment is composed of 99.8wt% CoNiCrMo alloy matrix and 0.2wt% nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=35at%; Ni=35at%; Cr=20at%; Mo=9at% The preparation method of the multi-principal alloy in this embodiment includes the following steps: S1: Batching and smelting According to the target composition ratio, 50 kg of single element raw materials of Co, Ni, Cr and Mo are calculated and weighed for use.

[0043] The uniformly mixed alloy elements and N element are placed in a vacuum induction furnace, and smelted under a pressure of 1500 kPa in an inert gas atmosphere to obtain an alloy mother ingot, which is then cast in a copper mold to obtain an alloy ingot; S2: Open forging The alloy ingot was forged at a final forging temperature of 1050°C into a 15mm thick flat steel. Samples were taken to test the uniformity of the composition, and the chemical composition met the alloy design standards.

[0044] S3: Solution treatment, hot rolling, heat treatment, cold rolling, annealing Solution treatment: keep the forged alloy flat steel in a heat treatment furnace at 1180°C for 60 minutes; Hot rolling: The alloy flat steel is immediately hot rolled after the insulation is completed, and the alloy flat steel is rolled for multiple passes. The final alloy thickness is rolled from 15mm to 7.5mm, and then water-cooled to room temperature to obtain a hot-rolled and cooled alloy plate; Heat treatment: keep the alloy plate in a heat treatment furnace at 1180°C for 1 hour, cool it to room temperature with water, and immerse the alloy plate in a 20% hydrochloric acid solution for pickling to remove the oxide layer on the alloy surface caused by hot rolling.

[0045] Cold rolling: The alloy plate after the oxide layer is removed is cold rolled, and the thickness of the alloy plate is rolled from 7.5 mm to 3 mm through multiple rolling passes to obtain an alloy cold rolled plate.

[0046] Annealing: The alloy cold-rolled plate cold-rolled to a thickness of 3 mm was annealed, and the alloy plate was annealed at 900°C for 5 min, 1000°C for 5 min, and 1100°C for 5 min in sequence, and then water-cooled to room temperature to obtain a cold-rolled annealed multi-principal alloy.

[0047] S4: Mechanical properties test of the obtained multi-principal alloy The alloy plates were cut into tensile specimens using an electric spark wire cutting machine, and the tensile mechanical properties of the alloy were tested using a universal mechanical testing machine at a test temperature of 77K.

[0048] At 77K, the alloy has a tensile strength of 1640MPa, a low-temperature yield strength of 1158MPa, and a plasticity of 31.5% after annealing at 900℃ for 5min. At 77K, the alloy has a tensile strength of 1562MPa, a low-temperature yield strength of 1101MPa, and a plasticity of 25.5% after annealing at 1000℃ for 5min. The tensile strength of the alloy after annealing at 1100℃ for 5min at 77K is 1601MPa, the low-temperature yield strength is 965MPa, and the plasticity is 36.5%.

[0049] Example 3 Example 3 provides a multi-principal element alloy with added interstitial atoms and a preparation method thereof.

[0050] The difference between Example 3 and Example 1 is that the multi-principal alloy is composed of 99.7wt% CoNiCrMo alloy matrix and 0.3wt% nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=35at%; Ni=35at%; Cr=20at%; Mo=9at%.

[0051] The alloy plates were cut into tensile specimens using an electric spark wire cutting machine, and the tensile mechanical properties of the alloy were tested using a universal mechanical testing machine at test temperatures of 77K and 298K.

[0052] The properties of the multi-principal alloy in Example 3 at 77K are as follows: tensile strength is 1539MPa, yield strength is 857MPa, and plasticity is 61%.

[0053] The properties of the multi-principal alloy at 298K in Example 3 are: tensile strength 995MPa, yield strength 493MPa, plasticity 50% The remaining parameters of the above embodiment are the same as those of embodiment 1.

[0054] Performance testing Figure 2 This is an electron backscattered diffraction (EBSD) image of the microstructure of the solid solution multi-principal alloy with interstitial atoms added in Example 1 of the present application. By analyzing the EBSD image, it can be seen that the alloys prepared in Example 1 all show a single FCC phase feature and equiaxed grains.

[0055] Figure 3 3 is the tensile stress-strain curve of the solid solution multi-principal alloy with added interstitial atoms prepared in Example 1. Figure 4 : is the tensile stress-strain curve of the cold-rolled annealed multi-principal alloy with added interstitial atoms obtained in Example 2. Figure 3 , Figure 4Analysis shows that the alloy obtained by solid solution and cold rolling has excellent low-temperature mechanical properties. By introducing a certain amount of nitrogen into the FeCoNiCrMo alloy, an interstitial solid solution is formed with the matrix. Through the solid solution and cold rolling processing technology, the alloy is recrystallized, twins can be induced under low temperature conditions, and the interstitial atomic stable phase structure and multiple dislocation mechanisms induce plastic enhancement. The multiple strengthening effects further improve the strength and plasticity of the alloy.

[0056] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A multi-principal alloy with added interstitial atoms, characterized in that: The invention is composed of a CoNiCrMo alloy matrix with a weight ratio of 99.7-99.9wt% and a nitrogen element with a weight ratio of 0.1-0.3wt%; Calculated by atomic percentage of the elements, the composition of the CoNiCrMo alloy matrix is: Co=33-37at%; Ni=33-37at%; Cr=18-22at%; Mo=7-11at%.

2. The multi-principal alloy with added interstitial atoms according to claim 1, characterized in that: The invention is composed of 99.75-99.85wt% of CoNiCrMo alloy matrix and 0.15-0.25wt% of nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=34-36at%; Ni=34-36at%; Cr=19-21at%; Mo=8-10at%.

3. The multi-principal alloy with added interstitial atoms according to claim 1, characterized in that: The invention is composed of 99.75-99.85wt% CoNiCrMo alloy matrix and 0.15-0.25wt% nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=34-36at%; Ni=34-36at%; Cr=19-21at%; Mo=8-10at%; P<0.001at%; S<0.0015at%.

4. The method for preparing a multi-principal-element alloy with added interstitial atoms according to any one of claims 1 to 3, characterized in that: Specifically, the following steps are performed in sequence: S1: The materials are prepared according to the target composition ratio, and then placed in a vacuum pressure induction furnace, pressurized to 10-20 bar in an inert gas atmosphere for smelting to obtain an alloy mother ingot, which is then cast in a copper mold to obtain an alloy ingot; S2: Forging the alloy ingot to obtain alloy flat steel; S3: performing a solid solution treatment on the alloy flat steel treated in step S2 to obtain a solid solution multi-principal alloy; Alternatively, the alloy flat steel treated in step S2 is sequentially subjected to solid solution treatment, hot rolling treatment, heat treatment, cold rolling treatment, and annealing treatment to obtain a cold-rolled annealed multi-principal alloy.

5. The method for preparing a multi-principal alloy with added interstitial atoms according to claim 4, characterized in that: In step S2, the blank forging temperature is 950-1150°C.

6. The method for preparing a multi-principal alloy with added interstitial atoms according to claim 4, characterized in that: In step S3, the solution treatment is specifically: keeping the temperature at 1100-1200° C. for 50-70 minutes.

7. According to claim 4, it is characterized in that In the preparation method of a multi-principal alloy with added interstitial atoms, in step S3, the hot rolling treatment is specifically: a hot rolling reduction rate of 45-55%, multiple rolling passes, water cooling to room temperature, and obtaining a hot-rolled and cooled alloy plate.

8. The method for preparing a multi-principal alloy with added interstitial atoms according to claim 4, characterized in that: In step S3, the heat treatment is specifically: keeping the temperature at 1100-1200° C. for 0.5-2 h, then cooling to room temperature and pickling.

9. The method for preparing a multi-principal alloy with added interstitial atoms according to claim 4, characterized in that: In step S3, the cold rolling process is specifically: the cold rolling reduction rate is 10-90%, and multiple rolling passes are performed.

10. The method for preparing a multi-principal-element alloy with added interstitial atoms according to claim 4, characterized in that: In step S3, the annealing treatment is specifically: annealing at 800-900° C. for 2-20 min.

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